China's top drug regulator approved a domestically developed innovative breast cancer drug for expanded use on Wednesday, offering a new first-line treatment option for patients with a common subtype of advanced breast cancer.

The drug, Culmerciclib capsules, was developed by Chia Tai Tianqing Pharmaceutical Group, a subsidiary of Sino Biopharmaceutical.

It has been approved by the National Medical Products Administration for use in combination with fulvestrant as a first-line treatment for hormone receptor-positive, HER2-negative, or HR+/HER2?, locally advanced or metastatic breast cancer, the company said.

The approval marks the second indication for Culmerciclib in China, extending its use from patients whose disease had progressed after prior endocrine therapy to the first-line treatment setting.

Culmerciclib is the world's first CDK2/4/6 inhibitor, according to the company. CDK inhibitors are targeted cancer drugs designed to block proteins that cancer cells rely on to grow and divide.

The drug was previously approved in last December, also in combination with fulvestrant, for HR+/HER2? breast cancer patients after endocrine therapy. It has since benefited more than 1,000 patients in clinical practice, according to the company.

Breast cancer is the most common cancer affecting women globally and in China. HR+/HER2? breast cancer accounts for about 65 to 70 percent of all breast cancer cases, the company said.